Available-for-sale securities (Tables)

3 Months Ended

Mar. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Summary of Available-for-Sale Securities at Estimated Fair Value

The following table is a summary of available-for-sale securities recorded in cash and cash equivalents or marketable securities in our Condensed Consolidated Balance Sheets (in millions):

	March 31, 2015									December 31, 2014
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Money market funds	$	7,683	$	—	$	—		$	7,683	$	7,926	$	—	$	—		$	7,926
Corporate debt securities	1,885		4		(1		)	1,888		941		—		(3		)	938
U.S. treasury securities	1,340		2		—			1,342		363		—		—			363
Residential mortgage and asset-backed securities	516		—		—			516		269		—		—			269
U.S. government agencies securities	210		—		—			210		113		—		—			113
Certificates of deposit	71		—		—			71		—		—		—			—
Non-U.S. government securities	37		—		—			37		—		—		—			—
Municipal debt securities	27		—		—			27		16		—		—			16
Total	$	11,769	$	6	$	(1	)	$	11,774	$	9,628	$	—	$	(3	)	$	9,625

Summary of the Classification of Available-for-Sale Securities

The following table summarizes the classification of the available-for-sale securities on our Condensed Consolidated Balance Sheets (in millions):

	March 31, 2015		December 31, 2014
Cash and cash equivalents	$	7,895	$	7,926
Short-term marketable securities	659		101
Long-term marketable securities	3,220		1,598
Total	$	11,774	$	9,625

Summary of Available-for-Sale Securities by Contractual Maturity

The following table summarizes our portfolio of available-for-sale securities by contractual maturity (in millions):

	March 31, 2015
	Amortized Cost		Fair Value
Less than one year	$	8,554	$	8,554
Greater than one year but less than five years	3,167		3,172
Greater than five years but less than ten years	37		37
Greater than ten years	11		11
Total	$	11,769	$	11,774

Summary of Available-for-Sale Securities in a Continuous Loss Position Deemed not to be Other-than-Temporarily Impaired

The following table summarizes our available-for-sale debt securities that were in a continuous unrealized loss position, but were not deemed to be other-than-temporarily impaired (in millions):

	Less Than 12 Months					12 Months or Greater				Total
	Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses		Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value
March 31, 2015
Corporate debt securities	$	(1	)	$	570	$	—	$	—	$	(1	)	$	570
Residential mortgage and asset-backed securities	—			239		—		5		—			244
U.S. treasury securities	—			112		—		—		—			112
U.S. government agencies securities	—			101		—		—		—			101
Non-U.S. government securities	—			24		—		—		—			24
Municipal debt securities	—			6		—		—		—			6
Total	$	(1	)	$	1,052	$	—	$	5	$	(1	)	$	1,057
December 31, 2014
Corporate debt securities	$	(3	)	$	802	$	—	$	—	$	(3	)	$	802
Residential mortgage and asset-backed securities	—			227		—		1		—			228
U.S. treasury securities	—			206		—		—		—			206
U.S. government agencies securities	—			22		—		—		—			22
Municipal debt securities	—			2		—		—		—			2
Total	$	(3	)	$	1,259	$	—	$	1	$	(3	)	$	1,260